Spring



UNITED STATES PATENT OFFICE SPRING Theodor Held,Uerdingen, Germany, assignor to the firm Ringfeder G. m. b. H., Uerdingen, Germany Application November 14, 1929, Serial No. 407,132, and in Germany November 20, 1928 4 Claims. (Cl. 267-47) My invention relates to improvements in Referring to the embodiment illustrated in springs, and more particularly in springs subject Fig. 1 of the drawing it will be seen that the to bending stresses. improved spring is composed of a plurality of lay- The object of the invention is to increase the ers in the manner of leaf springs which are prostrength of such springs by dimensioning them vided in the part of the cross-section subjected 60 in accordance with the different behaviour of to compression with one or more recesses A which the material of the spring in regard to the frein the form of grooves extend over the entire quently repeated tension and compression length of the leaf spring. These recesses A in stresses. It is a well known fact that the fracthe otherwise rectangular cross-section cause a tures of leaf springs due to fatigue invariably displacement of the neutral. fibre towards the 65 start in the fibres. subject to tension. This expart of the cross-section subject to tension. The perience was further confirmed by extensive exneutral fibre passing through the center of gravperiments and thorough researches in connecity S is indicated by the fine line NN. The tion with the so-called ring springs consisting distance e1 of the most strongly stressed tension of superposed outer and irmer rings which are fibres is smaller than the distance e2 of the most 7 subject to pure tension and compression strongly stressed compression fibres from the stresses respectively. Here also the fatigue deline NN so that the tension and comp s veloped only in the outer rings subjected to tenstresses of the outer fibres stand in the ratio sion while the inner rings at the same height of eizez.

2o subject'to compression were almost indestruct gs. 2 a d 3 w a bad Wagon spring 75 ible- The risk of fracture due to the fatigue of in side-elevation and cross-section through the the material may according to the present instrap a holding the individual leaves b of the vention be greatly reduced and the endurance Spring toget e The Outer Clips 0 Prevent the strength of springs subject to bending stresses lateral disp of the leaves the increased by a judicious adaptation of the maxitomary manner. so mum tension and compression stresses to the It will be understood that any other suitable properties of the material. In a spring rod subcross-sections may be chosen in which a greater J'ect to bending and the cross-section of which tr n th of the spri s is at a d y d fi r ntly is divided in two symmetrical halves by the dimensioning 61 and neutral fibres the tension and compression The nature of the inv is diagrammati- 85 stresses are equal. If, on the other hand, by a, cally illustrated in Figs. 4a and 4b. Besides a change of the cross-section the neutral fibre is n n prin cr s-s accordin to my i displaced from the middle towards the fibr vention such as for instance used for slotted subject to tension the maximum tension stresses in er rings of friction springs there is shown a are reduced for the same amount of bending ring piece in side-elevation which is subject to 90 while the maximum compression stresses inbending stresses. Here also S is. the center of crease. The ratio to be selected between tension gr y, the neutral fibre, 61 the distance and compression stresses depends upon the oscilof the fibre subject to maximum tension and c2 lation strength for these kind of stresses and that Of the fi subject t0 maximum eemplesthus changes with the material employed. The sion from the line NN. The distribution of the 95 invention is, however, intended to cover all other stresses will be gathered from the line OO' spring sections subject to bending stresses in located at right angles to NN in Co ju which the tension stresses are chosen lower than w t e l e indicating the Value and the the compression stresses with the object of in-. nature of the stresses in the fibres. Since the creasing the strength of the spring. stresses in all materials suitable for springs in- 100 In the drawing affixed to my specification my crease in proportion with the distance from the invention is illustrated by way of example. In neutral fibre, the maximum tension k'z must be the drawing smaller than the maximum pressure kd and-stand Fig. 1 is a cross-section through an embodiin the relation of e1 to ex. ment of my improved spring. I claim as my invention: 1 Fig. 2 is an elevation of a supportingspring .1. A spring of a material having equal refor railroad vehicles. sistance to static tensile and compressive strains Fig. 3 is a cross-section through Fig. 2, and v and having a' cross-section formation in which Figs. 4a and 4bare diagrams illustrating the the proportion of the distances of the outer tennature of my invention. sion fibres and the outer compression fibres from 3. A spring as claimed in claim 1, in which the material of the cross sectional portion subject to compression, is taken out in the form of grooves. A

4. A spring as claimed in claim 2, in which the material of the cross sectional portion subject to compression, is taken out in the form of grooves.

THEODOR HELD. 

